The saint’s works can be divided into four categories: rules for penitence and monastic life, letters, sermons, and poetry. In the years after the foundation of the Luxeuil monastery (593) Columban decided to adopt a rule for his monasteries. This strict and severe rule consisted of bodily punishment with a branch and daily study. The results were monasteries with well developed scriptoria and rich libraries to deepen the monks’ education.
Saint Columban’s monastic rule is comprised in two works. The first is Regula Monachorum, an essay on a monk’s fundamental virtues with spiritual advice divided into ten chapters. There are chapters on obedience, silence, food and drink, disdain for material goods, rejection of vanity, chastity, prayer, discretion, chagrin, and the monk’s perfection. The Regula Cenobialis has numerous chapters on monk’s faults and penitence. It regulates the monastery’s everyday life. Columban also wrote the Paenitentiale.
Today only six of Columban’s letters remain. One is addressed to Pope Gregorius Magnus, another to French bishops, others to Pope Sabinanus or Boniface III, his Luxeuil monks, Pope Boniface IV, and finally one to one of his young disciples. These works demonstrate the saint’s knowledge of rhetoric, complex words and refined style
There is some controversy about the authenticity of the sermons. Some scholars doubt their authorship; others find the peculiar writing traits of Saint Columban in thirteen of them. He is said to have composed these for his monks in the last years of his life between 613 and 615. The content is a catechesis.
Some poetry is also attributed to Saint Columban though the number is uncertain, between five and six works. These works demonstrate the saint’s classical education. Here the spirit is different from his other works as Columban shows his more human feelings over his severe and strict attitude.